Making a 1mm wide by 1mm Deep channel 2mm in from the edge and around the perimeter of a clean unvarnished spruce violin top

This channel would likely have the outer and inner lines lasered.

It can be done, using the right laser, but it will not be as pretty as your milled slot.

Was there a question here?

Trust me on this, “clean unvarnished spruce” will look awful after laser cutting / engraving / pocketing without careful attention to detail.

The problem is that a laser converts solid wood into powdered charcoal and blows the schmutz everywhere, including deep into the pores of that gorgeous unvarnished spruce. It will never ever come clean, because the charcoal never comes back out of those pores.

You may have some success by masking the surface using some variety of laser-friendly tape, but my (admittedly limited) experience suggests schmutz will penetrate the edges just enough to ruin the look. If you cannot afford any marks on the wood (and a violin surely falls into that category), then a laser is not the right hammer for the job.

I’d love to be proven wrong, but you should make many tests on scrap wood before trusting that you have the process well in hand.

With that in mind, actually cutting such a channel is straightforward. If you start with a CAD drawing, export the channel boundary as a DXF or SVG vector image, import it into Lightburn, offset as needed for the kerfs, set the layer to Fill, align the wood, and Fire The Laser.

You’ll need a bunch of Material Tests to find how much power / how many passes will convert 1 mm of wood into soot. Some test pieces using similar channels will tell you how much kerf to allow on the engraving to get the exact 1 mm width.

Posts on marquetry may be helpful:

Let us know how it works out!

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Not trying to discourage You one bit Curly, but:

I’d be willing to bet that even with careful attention to detail, the result will still look less than ideal.
The suggested masking with an inert cutting atmosphere may reduce charring, but its unlikely that the amount of work would be reduced at all.

^This *1000

Positioning the workpiece would also be extremely tricky, a jig would probably have to be cut with the same power up cycle and as a part of a same cutting file as the purfling channel cutting itself.
Even a fraction of a millimeter off, and it will look awful.

While i do perfectly understand the need to use a laser for a task like that, a purfling tool is still by far the best tool for that purpose.

In the not so distant past when the lasers didn’t yet exist in the luthiers toolbox, some folks wanted to use CNC routers.
Especially for the superb looking double purflings that are very tricky and time consuming to do by hand.
The same positioning accuracy problems plagued router approach as well, not to mention tool-loads, chipping, etc.
So back to the trusty purfling tool it was back then as well.



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